In my opinion, this was a terrorist attack

Jacques Moizan Euronav director

Yemeni authorities are trying to salvage the Limburg tanker, which is still burning in the Gulf of Aden, and say they are afraid of a major oil slick spreading along the Arabian coast.

But they have sought to play down allegations that the explosion was the result of an attack, saying a fire on board was the most likely cause.

The owners of the tanker, Euronav, say they believe their vessel was deliberately rammed by a smaller boat.

"In my opinion, this was a terrorist attack," Euronav director Jacques Moizan said. "The crew saw a high-speed vessel approaching on the starboard side.

"An explosion followed with fire."

All but one of the eight French and 17 Bulgarian crew members have been accounted for and many of them have been taken to hospital.

'Near impossible'

The Limburg's captain reported an explosion which was followed by a fire on Sunday morning as the ship came into the port of Aden from Iran.

The incident occurred just a week before the second anniversary of a terrorist attack blamed on al-Qaeda against the USS Cole near the same Yemeni port killed 17 US servicemen.

The USS Cole attack was blamed on al-Qaeda

An early response from a French diplomat at the embassy in the Yemeni capital, Sana'a, compared the Limburg disaster to the attack but, in a more cautious statement, the French Foreign Ministry said it was too early to say what had caused the explosion.

Captain Peter Raes, managing director of Euronav, told BBC News Online it would be "near impossible" for an accidental explosion to have taken place.

He said the Limburg was a new, double-hulled ship, and was barely moving at the time of the explosion, which happened during good weather.

He said that the force of the apparent impact had pierced both hulls and penetrated 7 to 8 metres into the cargo hold, which was loaded with crude oil.

He said that he did not believe that extent of destruction could have been caused unless the smaller craft had explosives on board, particularly as the kind of heavy crude oil the Limburg was carrying was not particularly flammable.

Al-Qaeda crackdown

The BBC's Heba Saleh says the Yemeni Government has been keen to shed its country's image as a safe haven for al-Qaeda militants.

So far, the authorities have arrested more than 100 suspected members of the group and of other Islamic organisations.

Those accused of the USS Cole attack are due to go on trial in the coming weeks.